<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <style>
        .box {
            width: 300px;
            height: 300px;
            margin: 40px auto;
            background-color: #2b92d4;
            border-radius: 5px;
            box-shadow: 01px2pxrgba(0，0，0，.3);
            animation: breathe 2700ms ease-in-out infinite alternate;
        }

        @keyframes breathe {
            0% {
                opacity: .2;
                box-shadow: 0 1px2pxrgba(255，255，255，0.1)
            }

            50% {
                opacity: .5;
                box-shadow: 0lpx2pxrgba(18，190，84，0.76)
            }

            100% {
                opacity: 1;
                box-shadow: 0lpx30pxrgba(59，255，255，1)
            }
        }
    </style>



</head>

<body>

    <div class="box"></div>
</body>

</html>